Ecological interactions

Question 1

The physical place where an organism lives

Answer 1

habitat

ex. tropical forest, grasslands

Question 2

niche

Answer 2

how an organism makes its living

ex.carnivore-hunts at dusk versus daylight

herbivores- feeds on woolly plants vs grasses

Question 3

Competition has —- and —- competition.

Answer 3

interspecific and intraspecific (within)

Question 4

Leibig’s Law of the Minimum

Answer 4

pop. numbers can be regulated by a single resource that has the greatest relative scarcity

ex.phytoplankton has limited iron and nitrogen

Question 5

Grinnell-1904 and Gaussian-1932

Answer 5

Evidence for interspecific competition

-give two species of paramecium and fixed amount of bacteria as food
-both showed logistic growth curve when separated but together one takes over the other

TWO SPECIES WITH THE SAME NICHE CANNOT COEXIST

Question 6

If competitive exclusion is true, why are there so many species in the same habitat using the same resources?

Answer 6

habitat diversity

Grain beetles
Calandra beetle takes over the rhisopertha in 29.1C but in 32.3C Rhiso takes all resources

-temp is always changing maybe this is why they can coexist

Question 7

Evidence for interspecific competition in nature?

Answer 7

1.Habitat shifts in allopathy and sympatry
2.Character displacement(ecological and reproductive)
3.Habitat differences and resource partitioning
4.Allelopathy

Question 8

EVIDENCE OF INTERSPECIFIC

1. Difference between allopathic and sympatric pop.

Answer 8

Allopatry= different home ( trout and char in separate lakes spread throughout)

Sympatry=same home( trout and char in same lake char only stays on bottom close to the shore and trout in center)

Question 9

EVIDENCE OF INTERSPECIFIC

2. What is character displacement?

Answer 9

the tendency for two species to diverge in form when in sympatry

ex. House Finch and black-headed Grosbeak -different size beaks b/c they live together

Question 10

EVIDENCE OF INTERSPECIFIC

2. What is the Hutchinson’s ratio?

Answer 10

Average Hutchinson’s ratio for sympatric species is 1.28
Mixed success in allying this

Question 11

EVIDENCE OF INTERSPECIFIC

3. Habitat differences and resource partitioning

-what is the ghost of competition past

Answer 11

It may look like there is competition but for example a forest how does all the different trees live in the same niche, they don’t have the same one. The roots under the soil take up different depths.

Question 12

EVIDENCE FOR INTERSPECIFIC

3. Habitat differences and resource partitioning

What is competition of the present?

Answer 12

-exotic species-artificial introducing a species into habitats they weren’t, leads to the displacement of native species that occupy similar habitats

ex. Scotch bloom introduced from Europe and now threatening native Garry Oaks

Question 13

EVIDENCE OF INTERSPECIFIC
4. What is alleopathy?

What is Salvia?

What other things in ocean do this?

Answer 13

chemical competition in plants and animals
-the release of chemicals by on species in order to reduce growth or survivorship of another species

ex. Black walnut trees secrete Juglone from the roots
Crops like barley secretes alkaloids which reduces weeds

Salvia produces volatile terpines(bad smell)- two boxes with cucumber seeds- add Salvia to one doesn’t grow, b/c birds came to eat

Coral reefs- alleopathy among corals creating levels

Question 14

Elton’s niche?

Answer 14

the role of a species in a community

Question 15

Hutchinson’s niche?
What are the two niches in this?

Answer 15

-all biophysical conditions that characterize the life of a species

1-Fundamental niche
2-Realized niche

Question 16

Fundamental vs realized niche

Answer 16

Fundamental- is the entire multidimensional space that represents the total range of condition within which an organism can function without limiting factors

Realized- the actual multidimensional space that a species can occupy taking into account biotic factors such as predators, competitors and parasites

Question 17

what is Lotka and Volterra competition model-1926

Answer 17

effect of species 2 on pop. growth of species 1

rN(K-N)-aN2/K

N2= pop. size of species 2

a=competition coefficient(alpha)
-if species 1=2. a=1

Question 18

What is biophagy?

Answer 18

consumption of bio material

Question 19

Survivorship Curves are largely due to..

Answer 19

predation

Question 20

What is the Functional response curves(FRC) measure?

Answer 20

rate of food consumption and density of prey

Question 21

What is Compensatory predation in FRC curve?

Answer 21

At low prey densities
a) reduced search efficiency
b) prey switching
c) search images(predator has a better image for more common prey)
d) aggregated responses of predators

Question 22

What is the threshold of security in a FRC curve

Answer 22

minimum density under which no further predation occurs

Question 23

What is the most important curve in FRC?

Answer 23

FRC #111- Multiple prey species eaten

Question 24

What age class do predators target?

Answer 24

mostly all predators target juveniles b/c of lowest cost of injury

-major exception to this trends is humans which target the largest

Question 25

Do predators limit maximum prey density?

Answer 25

Yes no. Predators don’t control prey density in long term. No statistical difference in numbers( Leibig’s law of minimum) ex. took all predators out of forest no different long term ex. Wolves keep caribou from exceeding K so yes they control density( if carrying capacity has been exceeded) ex. Muskrats that didn’t have territories are killed more No: if Leibig’s law of the minimum is acting Yes: if carrying capacity has been exceeded Yes: when native prey have no defenses against non-native predators

Question 26

Do predators limit maximum prey density? Parasitic wasps(parasitoids)

Answer 26

important natural source of biological control of population numbers in insect host wasp stings prey and control their movements into their burrow. Then wasp lays eggs, eggs eat organs for prey and make cocoon before breaking out

Question 27

Do predators limit maximum prey density? Non-native predators preying on native or non-native species

Answer 27

No opportunity for co-evolution between them and natural equilibrium is disrupted ex. Wild dogs(Dingos) preying on kangaroos. Dingos totally control density of kangaroos

Question 28

Relative abundance of predator and prey in a community What are the ratios?

Answer 28

Endothermic predators(warm blood).- 1:300 ratio for predator to prey Ectothermic predators( Relays on environment around them for body temp)- 60:300

Question 29

Exploitation rate of prey by each predator species

Answer 29

Average 5% for each predator species Biological interest= targets weak and young Biological capital- reproductive adults (Humans do this)

Question 30

Defences of prey against predators- First escape?

Answer 30

Camouflage or crysis Conspicuous

Question 31

Defenses of prey against predators Conspicuous, Why stand out? Mullerian? Batesian?

Answer 31

Warning(aposematic) colouration -usually poisonous Mullerian mimicry- when poisonous species mimic each other Batesian mimicry- when a harmless species mimic a harmful one

Question 32

Defenses of prey against predators What mechanism is the most frequent in arthropods(insects)?

Answer 32

Chemical

Question 33

Defence of plants against herbivores?

Answer 33

A) Plant structural defences -pointy B)Plant chemical defences-odour,irritation,bitter(very common)

Question 34

Animal defences against plant chemical defenses.

Answer 34

a) mixed function oxidaze b)concentration of toxins c) selective browsing